Carburetor ice responsive device



Dec. 21, 1948. w. H. KLIEVER CARBURETOR ICE RESPONSIVE DEVICE Filed Aug.23, 1943 I IN V EN TOR.

' to the degree of formation.

Patented Dec. 21, 1948 UNITED STATES PATENT OFFICE CARBUBETOR ICERESPONSIVE DEVICE Waldo H. Kliever, Minneapolis, Minn., asslgnor toMinneapolis-Honeywell Regulator Company, Minneapolis, Minra, acorporation of Delaware Application August 23, 1943, Serial No. 499,653

4 Claims. (Cl. 177-311) My present invention relates to a device whichresponds to ice formation within a carburetor,

the formation of, or melt the ice, upon an icing condition occurring.

One object of the invention is to provide an electronically operatedmechanism responsive to ice formation in a carburetor, by effectingvariation in the capacity of a condenser in proportion Another object isto provide said condenser in the'for'm of elements already constitutinga part of the carburetor so that additional elements need not be mountedin the air stream of the carburetor, thereby restricting the flowthereof. Also the weight of such additional parts is thus eliminated.

More specifically, it-is, my object to utilize the element of thecarburetor in the air stream thereof, such as the air screen, a venturi,a

throttle, or a turbulence bar; such element being insulated relative tothe carburetor wall, thereby forming the opposite plate of a condenserwith respect to such wall.

Still a further object is to provide several of the elements in the airstream of the carburetor as one plate of the condenser, by connectingthem in parallel so that an ice indicator is operated or a controlfunction performed upon the occurrence of ice on any one of suchcarburetor elements.

An additional object is to coat each of the elements in the carburetorforming the condenser plate opposed to the carburetor wall, withlnsulating material, thus preventing the possibility of short circuitingthe condenser by foreign objects entering the carburetor and bridgingthe venturi, throttle or turbulence bar. and the carburetor wall.

A further object is to provide an ice indicating and/or controlarrangement located at the first point oi impact of the air with thecarburetor or associated mechanism.

With these and other objects in view, my invention consists in theconstruction, arrangement ard type of aircraft carburetor showing myinvention applied thereto, and diagrammatically an electronic circuitconnected therewith for indi- 2 cating an icing condition and/orperforming a control function.

Figure 2 is a bottom plan view of the lower, end of the carburetorshowing particularly the turbulence bar thereof arranged to form oneplate of a condenser; and

Figure 3 is a sectional view on the line 3-3 of Figure 2 to show how theturbulence bar may be insulated with respect to the carburetor wall.

On the accompanying drawing, I have used the reference character C toindicate, in general, an aircraft carburetor, although, of course, myinvention may be applied to other devices. The carburetor shownis of astandard down-draft type. having a scoop 9 which connects to the throatl0 through which the air flows after flowing around and through aventuri V. The air then flows over the throttle T which is shownconventionally as the usual butterfly valve, and

finally over a turbulence bar B. The venturi V is ordinarily formed ofmetal such asaIuminum or brass, and is connected with the carburetorbody by a flange and screw connection (not shown).

Ice is formed in carburetors or the appurtenances thereto in at leastthree different manners. So-called impact ice is formed where the airfirst enters the carburetor or attachments. This impact ice may form inthe bend (not shown) of the scoop 9 or, if a screen is used in the scoopsuch as the screen S, the impact ice may be formed on such screen. Wherea supercharger and intercooler are utilized ahead of the scoop andscreen, it may be desirable to provide means to detect the presence ofice at whatever point the air originally enters the apparatus. Ice isalso formed as a result of expansion of the air. This may occur, forexample, when the air passes through the throttle of the carburetor.Again, ice is formed by reason of the evaporation of gasoline in thecarburetor and the consequent cooling action brought about by suchevaporation. Such ice can form when the temperature of the entering airis well above freezing and may form, for

example, on the turbulence bar (if used) or on the denser as it is onlynecessary, in order to have a condenser, that two conducting elements,whether plates or some other shape, be spaced with air or otherdielectric between them. In this manner, a pickup is provided at thefirst point of impact of the air.

In the Joint between the venturi and the carburetor body, I place agasket I2 of insulating material, and, of course, the screws that holdthe venturi in place are suitably insulated in the manner hereinafterdescribed for the screws I4 in Figure 3 that hold the turbulence bar Bin position. Thus the venturi V may form one plate element of acondenser while the carburetor wall W forms the other plate elementthereof. In some ar rangements, the venturi V may represent the firstpoint of impact of the air The throttle T may also be insulated as withinsulating strips I in the slot of the throttle stem I8. Thus, a pick-upis provided to detect ice formed as a result of expansion of the airpassing through the throttle.

With respect to the turbulence bar B, some carburetors are provided withsuch bars and some are not. In some types of carburetors. these bars aretermed X bars, and are for the purpose of forming a shield for theatomized fuel issuing from the nozzle openings 20 of the nozzle 22. Thefuel is sprayed in a direction substantially parallel to the downstreamside of the turbulence bar, and the bar effects a turbulence that moreeffectively and efficiently atomizes the fuel, and distributes itthroughout the air stream flowing through the carburetor.

In order to insulate the turbulence bar B from the carburetor body, aninsulating'sleeve 24 (see Figure 3) may be provided around the base ofthe nozzle 22 and an insulating gasket 20 may be interposed between theturbulence bar and the center boss 28 of the carburetor.

Under the heads of the screws I4 I also provide insulating washers 30,and the openings 32 for the screws where they pass through the centralpart of the turbulence bar B are enlarged to eliminate electricalcontact between the bar and screws. Thus, the wall W of the carburetor,or in fact the entire carburetor body, including the boss 20 of thenozzle 22 may constitute one plate element of a, condenser, whereas thebar B constitutes another plate thereof. In addition, the nozzle 22itself may be insulated from the remainder of the carburetor.

Any one of the elements S, V, T or B, or all of them if desired, as wellas an insulated nozzle may be utilized as one plate of the condenser.For this purpose they are connected in parallel by means of a wire 34shown diagrammatically in Figure 1, and a wire 08 is connected with thecarburetor. or grounded thereto whereby the carburetor body forms thesecond plate of the condenser. The wires 34 and 38 thereby provide apick-up circuit which may be utilized with any type of indicating and/orcontrolling apparatus, such for example as disclosed in my copendingapplication Serial No. 463,259, filed October 24, 1942, now Patent No.2,432,669, dated December 65 16, 1947. Such apparatus is generallyindicate at 31. The wire I02 thereof is connected to wire 3| and wireIOI is connected to wire 08. A condenser 38 is connected between wiresIOI and I03 and its capacity should equal that of the pickup 70 unitwhen there is no ice on any of the parts thereof. The indicator I30having needle I" will then indicate the degree of icing of the parts.

It is connected to the apparatus 31 by wires I20 and III. Also, acontrol device I01, for instance, 7

a heating means for the carburetor may be utilized so as to melt any icethat forms thereon. The heating means may comprise for instance aheating element I00 for the carburetor wall supplied with current from asource of supply such as a battery I40 and may obviously be of avariable type to furnish a greater degree of heat when icing is moreserious, as evidenced by greater increase in the capacity of thecondenser connected with the wires 04 and III. The control device I" hasone side connected to the apparatus 31 by wire I" while the other sidethereof is grounded.

In operation, the capacity of the pick-up condenser increases with theformation of ice and further increases as the thickness of the iceincreases. Ice does not need to form directly on the element used as adetector. Ice affects the condenser capacity as long as it forms at anypoint where there is some electrostatic field intensity as thatsurrounding any of the elements 8. V, T or B. Ice having a higherdielectric strength than air, icing causes the capacity of the condenserto increase and thereby varies the input circuit to the apparatus 31.

For a full description of the complete circuit used in connection withthe pick-up condenser of the kind herein disclosed, reference should behad to my previously mentioned copending application, Serial No.463,259, filed October 24, 1942. In said application a full descriptionof the electronic circuit and its operation are disclosed.

Each of the condenser elements 8, V, T and B (as well as nozzle 22 ifused as part of the pickup) is preferably coated with insulatin materialsuch as a phenolic coating. This is indicated at 40 on each of theelements V, T and B,'and shown by stippling where the parts show inelevation. No

attempt has been made to show the coating in cross-section. The purposeof the insulating coating 40 is to prevent a possible short circuit ofthe condenser through a foreign object drawn into the carburetor andbridging across from the venturi, the throttle or the turbulence bar tothe wall of the carburetor with resultant sparking. Also such a shortcircuit could occur across the turbulence bar and the nozzle 22. Byproviding 7 the insulation coating 40, the possibility of shortcircuiting the indicator I30 or the control means C out of properoperation is obviated.

In selecting an eiement of the carburetor to be used as one plate of thecondenser when the wall of the carburetor is used as the other one, Ihave selected elements which are preferably in, or at least have aportion thereof in, the center of the air stream. Ice formation occurshere first because the velocity is greater and there is no heat from theengine by conduction or radiation to keep the temperature up as therewould be if an element adjacent the wall of the carburetor wereprovided.- The variation in capacity of the condenser arrangementoccasioned by formation or presence of ice, may readily be used tooperate an'indioator such as at I30, or perform any control functiondesired in response to ice formation in the carburetor. The venturi, thethrottle and the turbulence bar are each very well adapted for thispurpose and may be used either separately or in any combination witheach other as desired.

Furthermore. by using elements already in the carburetor no additionalweight is added-an important consideration in aircraft, and noadditional parts are inserted in the carburetor to project into the airstream and thereby obstruct airflow.

Some-changes may be made in the construction and arrangement of theparts of my device without departing from the real spirit and purpose ofmy invention, and it is my intention to cover by my claims any modifiedforms of structure or use of mechanical equivalents which may bereasonably included within their scope without sacrificing any of theadvantages thereoi.

I claim as my invention:

1. In a device of the class described, in combination, a'carburetorhaving a metallic wall and a metallic venturi subject to the formationof ice, dielectric means spacing said venturi and said wall to comprisean electrical condenser whose capacitance is varied by the presence andthickness of said ice, and means for making electrical connection tosaid condenser.

2. In a device of the class described, in combination, a carburetorhaving a metallic wall, venturi, and throttle, said venturi and saidthrottle being subject to the formation of ice, dielectric means spacingsaid venturi andsaid throttle from said wall to comprise electricalcondensers whose several capacitances are varied by the presence andthickness of ice in their respective fields, and means for makingelectrical connection with said condensers in parallel.

3. In a device of the class described, in com- 30 bination: a carburetorhaving a metallic wall,

venturi, throttle, and turbulence bar, said venturi, throttle, andturbulence bar being subject to the formation of ice; dielectric meansspacing said venturi, said throttle, and said turbulence bar from saidwall to comprise electrical condensers whose several capacitances arevaried by the presence and thickness or ice in their respective fields;and means for making electrical connection with said condensers inparallel.

4. A device of the class described comprising, in combination: acarburetor having a metallic wall and a plurality of electricallyconductive members, including a venturi, a throttle, a turbulence bar,and a screen, cooperating to supply a combustible mixture 01 air and afluid fuel, said wall and said members being subject to the formation ofice; means insulating said members from said wall to comprise therewitha condenser whose capacitance is varied by the presence and thickness ofsaid ice; and means for making electrical connection to said condenser.

WALDO H. KLIEVER.

REFERENCES CITED The following references are of record in the

